Motor fuel stabilization



comprising substances which when dissolved in like. A second object is to provide a novel labor hydrocarbons and gum-forming constituents Patented Aug. 23, 1938 ES PATENT OFFICE 'MOTOR FUEL STABILIZATION No'Drawing. Application January 17, 1936, Serial No. 59,600

3 Claims. (Cl. 44--9) This invention relates to the stabilization of employed according to our process is substantialmotor fuels and more particularly to processes ly less than one per cent of the motor fuel. Howfor incorporating gum inhibitors into cracked ever, the proportions employed may be varied gasoline and the like. within rather wide limits.

Motor fuels, particularly gum-forming gaso- In order to test the results obtained according 'lines, are generally produced by subjecting hyto our process samples of gasoline containing no drocarbons to high temperature processes known inhibitor, of the same gasoline containing inas cracking, and then distilling off the lower boilhibitor, and of the same gasoline which has been ing portions thereof. The resulting products are redistilled after addition of the inhibitor, were oftentimes subjected to repeated distillations to subjected to the Oxygen bomb test proposed produce a motor fuel distilling within a certain by Voorhees and Es'singer in their paper entitled definite range. Motor fuels, as thus produced, Importance and significance of gum in gasoare generally comprised of a complicated and line, appearing in Proc. Am.- Pet. Inst. 10, Sec. indefinite mixture of saturated and unsaturated II, 169 (1929). Briefly this test consists in heating 25 cc. of gum free gasoline under an oxygen atmosphere in a rubber stoppered glass flask at C. After the heating has proceeded for a certain length of time gum begins to form, continued heating causes the gum to form at an increased rate. After heating for a predetermined period the gasoline is evaporated off in an inert atmosphere and the residue of non-volatile matter is weighed, The non-volatile matter comprises the gum formed and the amounts produced by the different samples of gasoline is a measure of the gum-forming tendencies of the gasoline. Gum-forming gasolines containing gum inhibitors form lesser amounts of gum than the same gasoline containing no inhibitor and the difference is a direct measure of the efliciency of the inhibitor.

In order to illustrate our invention and the preferred mode in which we carry the same into effect, and the advantageous results obtained thereby, the following examples are given:

Example 1 To a sample of freshly distilled unsaturated gasoline was added 0.006% by weight of pure para-amino-phenol, the para-amino-phenol only partially dissolved, large portions of it remaining suspended in the gasoline and the gasoline discolored considerably after standing for only a very short time. A portion of the gasoline con taining para-amino-phenol was redistilled and subjected to the Oxygen bomb-test together with a sample of the inhibited unredistilled gasoline and a control sample of the original uninhibited gasoline. The control sample gave 295mg. gum per 25 00., the inhibited gasoline gave 23 mg. gum per 25 cc. and the inhibited redistilled gasoline gave 18 mg. gum per 25 cc. It is clear, therefore, gum forming motor fuels treated with p-aminophenol according to our in- }Vention have excellent gum stability. Further,

UNITED STAT which on standing and subjection to the action of light and air have a tendency to form nonvolatile, insoluble, gummy and resinous products. These gummy and resinous products are highly objectionable in motor fuels for obvious reasons.

Accordingly it has heretofore been found necessary to remove such gummy products and the constituents which tend to form the same, from the gasoline by various processes. However, a large part of these gum-forming constituents have a high fuel value provided they can be prevented from forming gum. This has given rise to the development of so-called gum inhibitors the motor fuel tend to inhibit'the formation of gum therein. These gum inhibitors are, as a general rule, relatively insoluble in the motor fuel thereby makingit extremely difficult to incorporate the required amounttherecf into the fuel requiring the employment of long and tedious processes and expensive apparatus.

object of this invention is to stabilize motor fuels such as crude cracked gasolines and the and. time-saving process for adding gum inhibitors to motor fuels. A'furtherv object is to provide a process which will eliminate the presence. of preformed gum in motor fuels. Other objects will appear in the following description of our invention.

These objects are accomplished by the following invention which comprises distilling a motor fuel, such as a gum-forming gasoline, in the presence of a gum inhibitor. Our invention is based on the discovery that, when a gum inhibitor is admixed with the gasoline and the mixture is distilled, a distillate motor fuel product is obtained having excellent gum and color stability.

Ordinarily the amount of the gum inhibitor of the distillate obtained by our process apparently does not result wholly from the presence of the inhibitor in the distillate because only com-' paratively small amounts of the inhibitor, on the order of 0.0004%, pass over with the distillate said amount ordinarily being insuificient to impart the gum stability indicated by the above test.

Upon examination and comparison of the samples of the inhibited unredistilled gasoline and the inhibited redistilled gasoline, when paraamino-phenol was employed as the inhibitor, it was noted that the inhibited unredistilled gasoline was deeply colored, contained suspended matter and, upon exposure to light, readily darkened in color. On the other .hand, the inhibited redistilled gasoline was perfectly clear and free from suspended matter and had only a slight yellowish tint which, upon subjection to light, almost completely disappeared and the gasoline became almost colorless. No explanation can be offered for this phenomenon.

Erample 2 In another test, data were obtained to show the color stabilizing effect of the para-aminophenol upon the gum-forming motor fuel prepared by our process. In the table given below, sample 1 is the control sample of gum-forming gasoline, without anadded inhibitor, distilled under the same conditions as sample 3. Sample 2 is an undistilled sample of the control to which 0.005% of p-aminophenol was added. Sample 3 is another portion of the control sample to which 0.005% p-aminophenol was added and then distilled. After distillation, sample 3 contained only about 0.0004% of p-amino phenol. each sample was measured in the Saybolt chromometer, before and after exposure to sunlight. The results of these tests were as follows:

Saybolt color Sample No.

L Before gg f exposure for 3 hrs.

1. Distilled, no p-aminophenol +11 +10 2. U ndistilled, 0.005% aminophenol +9 2 3. Distilled from 0.005 a p-aminophenol +19 +16 The color of more, we have determined that the gum stability as color stable as the original gasoline. However, the ortho-aminophenol had a much less effect on the gum stability of the gasoline than the paminophenol but rendered the gasoline much more responsive to stabilization with subsequently added inhibitors.

v Many difierent methods of adding the gum inhibitor to the motor fuel may be employed, for example, the'gum inhibitor may be dissolved or suspended in the gasoline before the liquid is placed in the still, the inhibitor may be put into the still in solid form before the start of the distillation. Any one of these methods may be used successfully, the method to be employed depending upon the desire of the user.

This method is particularly adapted for use in original production of gum-forming gasoline and similar motor fuels. In such process the inhibitor should be added subsequent to any cracking" or other high temperature process to which the motor fuel is subjected, and prior to or during the final distillation thereof, thereby making it unnecessary to subject the motor fuel to any subsequent, involved and expensive process to stabilize the same. Furthermore, motor fuels obtained by our process are free from "preformed gum. This is of.advantage as it provides a gasoline which, as a general rule, has a lower gum content after ageing. Accordingly the scope'of our invention is to be limited solely by the appended claims construed as broadly as is .permissible in view of the prior art.

This application is a continuation ,in part of .our copending application Serial No. 595,227, filed February 25, 1932.

We claim:

1. The method of producing a gum and color stable motor fue1* containing cracked gasoline which comprises adding a small proportion of para-aminophenol to a crude cracked hydrocarbon distillate and distilling the resulting admixture to obtain a motor fuel containing cracked gasoline which is gum and color stable.

2. A method of producing a gum and color stable motor fuel containing constituents which normally form gum on storage, which comprises adding to said motor fuel a small proportion of para-aminophenol and then distilling the resulting admixture to obtain a motor fuel which is gum and color stable.

3. A method of producing a gum and color stable motor fuel containing constituents which normally form gum on storage, which comprises adding to said motor fuel a small proportion of a member of the group consisting of para-aminophenol and ortho-aminophenol and then distilling the resulting admixture to obtain a motor fuel which is gum and color stable.

RICHARD G. CLARKSON. CLAUDE G. WOLFF. 

